Otto Krabbes Square. Natural green wall

Roof water managed via natural wallThe end wall of a property with 10 apartments is faced on the bottom half (up to the 2nd and 3rd floors respectively) with one to two extra layers of brick in an artistic design. Old, reused bricks have been used, laid in such a way that they create small ledges where plants can easily establish themselves. In several places, there are openings for cavities behind the brickwork to provide nesting sites for birds. As this is a south-facing wall, wire has been set up for climbing plants in front of the brickwork and on both sides of the balconies up to the 4th floor. The plants will provide shade and cooling, as well as framing the blue surfaces where the water runs down twice a day.

The water from 230 m2 roof is collected and fed to a 12 m3 water tank. From this water tank, the rainwater is pumped up to 2nd and 3rd floor height, from which it runs down a number of blue 'waterfalls' and 'overruns' a little on the way down in order to promote plant growth. The water flows down into an open basin via a meandering 'brook' which runs along the gable and ends in a small pond overflowing to the water tank. The water tank has an overflow to a soakaway without overflowing to sewers.

Statement from Marijke Zwaan, ByhaveNetvÅ rket: The green wall, or 'natural wall', can be regarded as a vertical organic water garden that enriches the local environment.

Establishment costsAs all the rainwater from the property is drained locally, residents have been refunded their share of the connection charge for rainwater.

Operation and maintenanceThe Den Vertikale Have (The Vertical Garden) association is responsible for this. But as the brickwork is sited in Otto Krabbes Plads, Copenhagen Municipality is responsible for the upkeep of the beds and the attachments in front. The association bears responsibility for 10 years, after which time it will pass to the Municipality. Maintenance finance is derived from the refund from the sewer connection charge and from donations from many private enterprises and individuals.